GSSAPI or Generic Security Service Application Programming Interface allows login to an SSH server via alternative mechanisms such as Kerberos.
It's useful for those who need the feature, but it's enabled by default and could unnecessarily slow the overall login process if you only use the standard password or public-key authentication methods.
You can disable or enable GSSAPI authentication for SSH via GSSAPIAuthentication directive in your SSHd configuration.
Specifies whether user authentication based on GSSAPI is allowed. The default is no.
Related: How to accelerate SSH authentication
$ sudo vi /etc/ssh/sshd_config [sudo] password for user:
Add the line if it doesn't already exist and remove # at the beginning of the line if it exists.
$ sudo systemctl restart sshd
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